$ { \left[\begin{array}{rr}{-1} & {0} \\ {-2} & {0} \\ {1} & {-1}\end{array}\right]+\left[\begin{array}{rr}{-1} & {3} \\ {3} & {0} \\ {1} & {4}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}+{-1} & {0}+{3} \\ {-2}+{3} & {0}+{0} \\ {1}+{1} & {-1}+{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-2} & {3} \\ {1} & {0} \\ {2} & {3}\end{array}\right]}$